Tool67 checks runtime/provider availability for supported workflows. If a self-hosted GPU node is offline, a provider is unhealthy, or a workflow has been disabled by an administrator, the related model may be hidden from the selector.
This is intentional: it prevents users from starting a job that cannot currently run. When the runtime is healthy again, the option can return automatically.
If a model remains unavailable, choose another model shown on the page or try again later.